On November 5, 2009, an Army psychiatrist stationed at Fort Hood, Texas shot and killed 12 fellow soldiers and a civilian Defense Department employee while wounding 29 others. US Army Major Nidal Malik Hasan, the American-born son of two Palestinian immigrants, reportedly shouted “Allahu Akbar!”—“God is great!”—before launching his 10-minute shooting rampage at the Soldier Readiness Center. The shooting—the worst ever on an American military base—occurred as Hasan was facing imminent deployment to Afghanistan. A civilian police officer shot Hasan and placed him under arrest.

In the investigation that followed, the FBI and Defense Department investigators found that Hasan had been communicating with Anwar al-Aulaqi (sometimes spelled "al-Alwaki"), an American radical Islamic cleric living in Yemen. In the process of reviewing the evidence, investigators found that the FBI’s Joint Terrorism Task Forces in San Diego and Washington, DC had been aware of Hasan’s interactions with Aulaqi for over 11 months before the attack. Yet Hasan had never even been interviewed about his connection with the imam who would later be tied to “underwear bomber” Umar Farouk Abdulmutallab and to attempts to bomb US bound cargo planes with explosives packed in laser printer cartridges. (al-Aulaqi would later be killed by a US drone strike in Yemen.)